Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
During operation of a wind turbine, the rotation of the rotor blades through air generates aerodynamic noise. Due to the amplitude modulation (i.e., the peak-to-peak variation) of the aerodynamic noise, a “swooshing” or periodic pulsing sound is typically heard in the near field of the wind turbine (i.e., the area directly around the wind turbine). Such amplitude modulation is always present to some extent and, thus, is considered a normal and expected result of wind turbine operation. However, under certain conditions, an abnormal amplitude modulation effect can be heard in the far field (i.e., locations a certain distance (e.g., 1-4 kilometers) away from the wind turbines) that produces a “thumping” or “flapping” sound. This abnormal amplitude modulation has been described as having a more impulsive sound characteristic than that of the “swooshing” sound typically produced during operation of a wind turbine and, thus, is seen as a more of a nuisance to surrounding dwellings, residential communities and/or other populated areas. However, there is no system and/or method currently available that addresses this abnormal amplitude modulation effect.
Accordingly, a system and method for controlling the abnormal amplitude modulation of noise generated by a wind turbine would be welcomed in the technology.